Enhancing security level against potential internal eavesdroppers in Non-Orthogonal Multiple Access (NOMA) has been reported as a serious challenge. In this letter, a novel secure NOMA scheme based on physical-layer security concepts is proposed. The proposed scheme exploits the random and independent channel characteristics to induce a different phase shift in each user's symbol. Based on the assumption that the instantaneous channel phase between a user and the base station is available only at both ends, other users will not be able to decode the right symbol. Analytical and simulation average bit error rate performance results demonstrate the ability of the proposed scheme to degrade the performance at the eavesdropper without affecting the performance at other legitimate users and guarantee data confidentiality of each user.
Enhancing security level against potential internal eavesdroppers in Non-Orthogonal Multiple Access (NOMA) has been reported as a serious challenge. In this letter, a novel secure NOMA scheme based on physical-layer security concepts is proposed. The proposed scheme exploits the random and independent channel characteristics to induce a different phase shift in each user's symbol. Based on the assumption that the instantaneous channel phase between a user and the base station is available only at both ends, other users will not be able to decode the right symbol. Analytical and simulation average bit error rate performance results demonstrate the ability of the proposed scheme to degrade the performance at the eavesdropper without affecting the performance at other legitimate users and guarantee data confidentiality of each user.
This paper investigates the physical layer security of a downlink non-orthogonal multiple access (NOMA) communication system, wherein a base station is communicating with two paired active users in the presence of an eavesdropper and multiple idle nodes (helpers). In order to enhance the secrecy performance, a two-phase harvest-and-jam null-steering jamming technique is deployed. In the first phase, the base station provides the helper with power in addition to active users and eavesdropper’s information via simultaneous wireless information and power transfer technique. The helpers exploit the harvested energy and the information received in the first phase to build a null-steering beamformer and jam the eavesdropper, during the information exchange between the base station and the legitimate users in the second phase. A game theory is introduced to the proposed scheme, and the base station-helpers interactions are modeled as a Stackelberg game, where the helpers play the leader role and the base station is the follower. The utility functions of both the leader and follower are formed, and the Stackelberg equilibrium is reached by means of the backward induction technique. The proposed scheme demonstrates better secrecy performance when compared with the artificial noise-aided secure NOMA system.
This article presents a physical layer security (PLS) technique for non-orthogonal multiple access (NOMA), which can provide joint secrecy, fairness, and bit error rate (BER) improvement. The approach employs power hopping (PH), where users’ power coefficients are dynamically varied according to the instantaneous channel conditions. By randomizing both the detection order and the effective power allocation, PH obscures the underlying NOMA structure from a passive eavesdropper (Eve), thereby severely degrading the data detection capability. To enable secure coordination, a precoding-based mechanism is developed for sharing the PH patterns among legitimate users, leveraging the random and independent nature of wireless channels. The BER and secrecy outage probability (SOP) of the proposed framework are analytically characterized and compared to conventional NOMA under various channel and eavesdropping configurations. The obtained analytical results, corroborated by Monte Carlo simulations, confirm the effectiveness of the proposed scheme, where the SOP of legitimate users is never compromised regardless of Eve’s channel conditions, while incurring only negligible additional complexity compared to conventional NOMA. Furthermore, the fairness and BER performance of stronger users are significantly improved through the combined use of PH and optimal power allocation.
This paper presents a novel physical layer security (PLS) scheme for non-orthogonal multiple access (NOMA) systems that jointly enhances secrecy and bit error rate (BER). The proposed approach leverages power hopping (PH), wherein users’ power coefficients are dynamically allocated to obscure both the decoding order and actual power allocation from potential eavesdroppers. This uncertainty significantly reduces the feasibility of successful interception. Analytical expressions for the BER and secrecy outage probability (SOP) are derived under diverse channel conditions and eavesdropping scenarios. The theoretical findings, validated through Monte Carlo simulations, confirm that the proposed scheme robustly preserves the secrecy of legitimate users regardless of the eavesdropper’s channel quality. Moreover, the approach yields substantial improvements in both BER and SOP, particularly for the near user.
Abstract With the exponential growth of wireless communication technologies, ensuring the confidentiality of transmitted data has become paramount. This paper introduces a cutting-edge encryption scheme utilizing Non-Orthogonal Multiple Access (NOMA) for secure key generation. It proposes a method that utilizes an identical secret key derived from channel randomness and distance to prevent eavesdropping in NOMA communication, thus enhancing the system's resistance against potential attacks. NOMA is employed to simultaneously serve multiple users at the same time and frequency resources by applying different power levels to each user. In the proposed encryption scheme, NOMA principles combine channel randomness and user-base station distance in a non-orthogonal manner. This approach allows the generation of identical encryption keys shared by multiple users, ensuring an efficient and robust security mechanism benefits increased spectral efficiency and an improved system. The non-orthogonal of the generated encryption key enhances the security level, as it becomes harder for eavesdroppers to intercept and decipher the key. Integrating NOMA in the key generation process introduces an additional layer of unpredictability, further bolstering security. Extensive simulations and analyses were conducted to assess the proposed NOMA-based dual key extraction performance. A qualitative comparison between sources and a new proposed direction shows the Secrecy rate, key secrecy capacity, and secrecy outage probability demonstrate its effectiveness in providing a high level of security while incurring minimal overhead on the communication system.
Non-orthogonal multiple access systems will face serious physical layer security (PLS) problems in the present of internal eavesdropper. However, in the existing schemes, it's difficult to always guarantee the positive secrecy rate of the system. To this end, we consider the PLS against internal eavesdropping in two-users scenario and the beamforming design and optimal power allocation problems are given. The developed analytical results demonstrate that the proposed scheme can absolutely achieve positive secrecy rate if provided sufficient power. Simulation results show that the performance of proposed scheme is better than the existing solutions.
Physical layer security of non-orthogonal multiple access (NOMA) systems has attracted great attentions. However, the impact of mobility on physical layer security of NOMA systems has not been well studied. In this paper, to fill this gap, we investigate the impact of random mobility on physical layer security of NOMA systems. Considering scenarios where a base station (BS) or access point (AP) communicates to two random mobile users with a passive eavesdropper in two concentric circles, we study the secrecy performance with combinations of two typical random mobility models: random waypoint (RWP) and random direction (RD). A general analytical framework to numerically calculate the average secrecy rates of NOMA mobile users under steady state is provided. By comparing secrecy performance of mobile users with static users, we find that RWP mobile users can achieve higher average secrecy rates than the users with other mobility combinations. Meanwhile, two types of secrecy fairness for mobile users are fully considered and we propose a novel sum average secrecy rate maximization problem, subject to average power limits and users' QoS (quality of service) requirements. Considering eavesdropper's channel state information (CSI) is unknown to BS, we propose a threshold power allocation strategy to improve the sum average secrecy rate of NOMA mobile users. Extensive numerical simulations are conducted to validate our model and theoretical analysis.